RE: Frozen Electronics: A Project for Beginners and Advanced Alike!

michaelkellett — Wed, 05 Feb 2014 08:59:01 GMT

Had a quick look at your frozen board layout, for version 2 you should consider swapping sides for the track from the processor to pin D4 and this will allow the ground pour to flow through to the crystal oscillator. (in general you should always attempt to make the ground plane continuous and jumper other things over it (on the other side in this case) - there are several other places where you join bits of ground plane with jumpers but this isn't very good - you won't see any problems at low frequencies, or probably even at processor frequencies, but you would have issues with EMC where you need to think about what happens at up to at least 1GHz) . The oscillator should have its own local decoupling capacitor. (and it's usual to keep the Q designator for transitors and MOSFETs, there isn't a universal designator used for oscillators but OSC and XT are common.)

The big loops of track going to E, R/W and RS don't help for EMC - try to keep the loop area as small as possible - once you are paying for a double sided board the vias cost between nothing and very little unless you are making millions of boards or need nS level timing.

The 10uF across the processor is not necessary (you've got 22uF a few inches away).